Parent-infant interaction trajectories in infants with an elevated likelihood for autism in relation to 3-year clinical outcome

Developmental antecedents of autism may affect parent-infant interactions (PII), altering the context in which core social skills develop. While studies have identified differences in PII between infants with and without elevated likelihood (EL) for autism, samples have been small. Here, we examined whether previously reported differences are replicable. From a longitudinal study of 113 EL and 27 typical likelihood infants (TL), 6-min videotaped unstructured PII was blind rated at 8 and 14 months on eight interactional qualities. Autism outcome was assessed at 36 months. Linear mixed-effects models found higher parent sensitive responsiveness, nondirectiveness, and mutuality ratings in TL than EL infants with and without later autism. PII qualities at 8 (infant positive affect, parent directiveness) and 14 months (infant attentiveness to parent, mutuality) predicted 3-year autism. Attentiveness to parent decreased between 8 and 14 months in EL infants with later autism. This larger study supports previous findings of emerging alterations in PII in this group and extends on this by detecting earlier (8-month) predictive effects of PII for autism outcome and a more marked trajectory of decreased social attentiveness. The findings strengthen the evidence base to support the implementation of early preemptive interventions to support PII in infants with early autism signs. Previous studies have found parent-infant interaction (PII) differences between infants with elevated likelihood (EL) and with typical likelihood (TL) for autism. This may be due to early changes in social communication skills. However, sample sizes have been small. Here, we investigated whether we could replicate previous findings including a new larger sample by looking at whether infants at EL differed from infants at TL in PII qualities at 8 and 14 months, and whether these qualities differed in those with from those without autism diagnosis at 3 years. This study found that the TL group was rated to have more mutual play and parents played with their infant more sensitively and less directively than the EL group (infants with and without later autism). PII qualities at 8 (infant positivity, parent directiveness) and 14 months (infant interest in parent, mutual play) differed between those with and without later autism. Between 8 and 14 months, the baby's interest in the parent during play reduced faster in infants with later autism. As well as showing similar results to previous research, the larger sample has allowed us to find earlier interactional differences (8 months) and developmental changes in social attention that statistically predict a later autism diagnosis. The study highlights the importance of supporting PII in parents of EL infants in the first year of life.